The diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other disorders has long been an area of intense investigation. Non-invasive methods for examining tissue are palpation, Thermography, PET, SPECT, Nuclear imaging, X-ray, MRI, CT, and ultrasound imaging. When the physician suspects that tissue may contain cancerous cells, a biopsy may be done either in an open procedure or in a percutaneous procedure. For an open procedure, a scalpel is used by the surgeon to create a large incision in the tissue in order to provide direct viewing and access to the tissue mass of interest. Removal of the entire mass (excisional biopsy) or a part of the mass (incisional biopsy) is done. For a percutaneous biopsy, a needle-like instrument is used through a very small incision to access the tissue mass of interest and to obtain a tissue sample for later examination and analysis. The advantages of the percutaneous method as compared to the open method are significant: less recovery time for the patient, less pain, less surgical time, lower cost, less risk of injury to adjacent bodily tissues such as nerves, and less disfigurement of the patient's anatomy. Use of the percutaneous method in combination with artificial imaging devices such as X-ray and ultrasound has resulted in highly reliable diagnoses and treatments.
Generally there are two ways to percutaneously obtain a portion of tissue from within the body, by aspiration or by core sampling. Aspiration of the tissue through a fine needle requires the tissue to be fragmented into small enough pieces to be withdrawn in a fluid medium. The method is less intrusive than other known sampling techniques, but one can only examine cells in the liquid (cytology) and not the cells and the structure (pathology). In core sampling, a core or fragment of tissue is obtained for histologic examination, genetic tests, which may be done via a frozen or paraffin section. The type of biopsy used depends mainly on various factors present in the patient, and no single procedure is ideal for all cases. However, core biopsies seem to be more widely used by physicians.
Recently, core biopsy devices have been combined with imaging technology to better target the lesion. A number of these devices have been commercialized. One such commercially available product is marketed under the trademark name MAMMOTOME™, Ethicon Endo-Surgery, Inc. An embodiment of such a device is described in U.S. Pat. No. 5,526,822 issued to Burbank, et al., on Jun. 18, 1996, and is hereby incorporated herein by reference.
As seen from that reference, the instrument is a type of image-guided, percutaneous, coring, breast biopsy instrument. It is vacuum-assisted, and some of the steps for retrieving the tissue samples have been automated. The physician uses this device to capture “actively” (using the vacuum) the tissue prior to severing it from the body. This allows for sampling tissues of varying hardness. The device can also be used to collect multiple samples in numerous positions about its longitudinal axis, and without removing the device from the body. These features allow for substantial sampling of large lesions and complete removal of small ones.
Co-pending application Ser. No. 08/825,899 filed on Apr. 2, 1997, which is hereby incorporated herein by reference, described other features and potential improvements to the device including a molded tissue cassette housing permitting the handling and viewing of multiple tissue samples without physical contact by the instrument operator. Another described therein is the interconnection of the housing to the piercing needle using a thumbwheel, to permit the needle to rotate relative to the housing, and preventing the vacuum tube from wrapping about the housing. During use, the thumbwheel is rotated so that the device rotates within the lesion, and samples can be taken at different points within the lesion.
In actual clinical use for breast biopsy the instrument (probe and driver assembly) is mounted to the three axis-positioning head of an x-ray imaging machine. The three axis-positioning head is located in the area between the x-ray source and the image plate. The x-ray machines are outfitted with a computerized system which requires two x-ray images of the breast be taken with the x-ray source at two different positions in order for the computer to calculate x, y and z axis location of the suspect abnormality. In order to take the stereo x-ray images the x-ray source must be conveniently movable. The x-ray source therefore is typically mounted to an arm which, at the end opposite the x-ray source, is pivotally mounted to the frame of the machine in the region of the image plate.
Recently, there has been a need for a hand held core sampling biopsy device. This need has been fulfilled by Ethicon-Endo-Surgery in U.S. Pat. No. 6,086,544 issued on Jul. 11, 2000, which is hereby incorporated herein by reference. The aforementioned patent discloses a hand held MAMMOTOME™. The aforementioned invention is handpiece in that the handpiece on the MAMMOTOME™ may be held approximately parallel to the chest wall of the patient for obtaining tissue portions closer to the chest wall than my be obtained when using an instrument that may be obtained when using an instrument that is mounted is manipulated by the operator's hand rather than by an electromechanical arm. Thus, the operator may steer the tip of the handpiece on the MAMMOTOME™ with great freedom towards the tissue mass of interest. The surgeon has tactile feedback while doing so and can thus ascertain to a significant, degree, the density and hardness of the tissue being encountered. In addition, a hand held MAMMOTOME™ is desirable because the handpiece on the MAMMOTOME™ may be held approximately parallel to the chest wall of the patient for obtaining tissue portions closer to the chest wall than may be obtained when using an instrument that is mounted to an electromechanical arm.
Recently, there has been a desire to use the above described biopsy devices with MRI imaging devices instead of x-ray imaging devices. However, existing medical biopsy sampling devices use small, multi-lumen probes extensively fabricated mostly if not entirely from metal. The metallic nature of these probes has many drawbacks. Typically these metal probes are electrically conductive and often magnetically weak, which interferes with their use under MRI guidance. The electrically conductive and magnetically weak nature of metal probes often work to create field distortions, called artifacts, on the image. The image of the lesion will show the metal probe, and this is problematic because the image of the probe can obscure the image of the lesion. Therefore, there has been a desire to have generally non-metallic biopsy probe of the type described above. However, elimination of the artifact created by the metal probe entirely is also problematic because physicians rely extensively on some type of artifact to notify them as to where the tip of the probe is relative to the lesion.